In recent years, thanks to the spread of digital still cameras, digital video cameras, and personal computers (PCs), individual users can now store a vast amount of digital content, such as still images and video.
Furthermore, technology such as film scanning has made it easy to digitalize analog content, such as photographs taken with a silver salt camera or video taken with an 8 mm camera, and store the digitalized content in a PC or the like.
The need thus arises for easy management of a large quantity of content stored in a location such as a PC. One possibility is for management based on the shooting date of the content or the shooting location. In the case of content captured with a digital still camera or a digital video camera, accompanying data such as the shooting date or shooting location can be acquired from Exchangeable Image File Format (Exif) data attached to the content. Information such as the shooting date or shooting location cannot be acquired, however, from digitalized content originally captured with a silver salt camera or an 8 mm camera. Furthermore, some digital still cameras and digital video cameras with low functionality do not have a Global Positioning System (GPS) function. In this case, accompanying data on the shooting location cannot be acquired.
To address this problem, Patent Literature 1 discloses technology to analyze a content and estimate the accompanying data that should be attached to the content. In Patent Literature 1, a plurality of similar registered images are extracted, the similar registered images having image feature amounts similar to the image feature amounts for an input image (content). Shared items are then extracted from among accompanying information for the plurality of similar registered images. If a shared item satisfies a predetermined condition, the shared item is set as accompanying data for the input image.